638 FAMILY: CRYPTOBIIDiE 



though most writers have placed it in Laveran and Mesnil's genus, Tnj- 

 panojjlasma, which was established by them in 1901. According to the rules 

 of nomenclature, Leidy had no necessity to change the name to Cryptoicus. 



Cryptobia helicis Leidy, 1846. — According to Belar (1916), C. helicis is 

 typically an elongate organism varying in length from 6 to 20 microns 

 (Fig. 262). The breadth varies considerably, there being comparatively 

 narrow forms not more than 3 microns in breadth and others which are 

 much broader. Typically, however, the organism has an elongate form. The 

 body is distinctly flattened. There is a nucleus consisting of a nuclear 

 membrane enclosing a space in which there is a central karyosome and a 

 number of scattered chromatin granules. Nearer the anterior end is the 

 kinetoplast, consisting of an elongate parabasal body and two blepharo- 

 plasts, which are often so close together as to appear as one. From each 

 there arises an axoneme. One of these passes through the cytoplasm to 

 the anterior end of the body, where it becomes a flagellum, w^hich is about 

 as long as the body itself. The other passes to the surface of the body 

 in a lateral or backward direction, and then runs over the surface of the 

 body, to which it is adherent, as far as the posterior extremity. It is then 

 continued in a short flagellum. There does not appear to be an undulat- 

 ing membrane at the line of attachment of the axoneme. 



The flagellate multiplies by binary fission. The process has been 

 described in detail by Belar. The single pair of blepharoplasts divides 

 to form two pairs, the original axonemes remaining with one pair, while 

 new axonemes commence to grow out from the other j)air. As the two 

 pairs of blepharoplasts separate, the parabasal body splits from before 

 backwards. At the same time changes take place in the nucleus. The 

 karyosome becomes elongated and dumb-bell-shaped, and its two halves 

 become more and more separated, though still connected by a fibre, as the 

 nucleus itself increases in length. The chromatin granules of the nucleus 

 at a certain stage appear to be collected at the equator of the nucleus as an 

 irregular plate. This plate is divided into two parts, which travel to 

 opposite poles of the nucleus. Finally, the nucleus is divided into two. 

 The nuclear division is thus a modified form of mitosis. By the time 

 nuclear division is complete, the flagellate has two complete sets of organs. 

 The body now divides, and two organisms result. Belar described what 

 he supposed to be conjugation, in which two flagellates unite, their nuclei 

 and kiuetoplasts fusing, but in a later paper (1924) he admits that this 

 was an erroneous interpretation of the appearances seen by him. 



1-4. Various types of flagellate. 5. Commencing division of nucleus. 



6-7. Divided blepharoplast and commencing division of parabasal. 



8. Blepharoplast and parabasal completely divided; nucleus dividing. 

 9-10. Pinal stage of division. 



